Battery-powered hot water recirculation pump

ABSTRACT

A relatively small water pump-DC motor combination, powered by batteries, provides sufficient pump power to create the flow between the hot and cold water lines necessary to maintain a substantially immediate hot water response when the hot water tap is opened. The pump is controlled by a thermal sensor signaling the pump to commence operation when the temperature in the hot water line upstream of the hot water tap is less than a predetermined value. Preferably, each of the batteries is rechargeable, most preferably utilizing a wireless system, where the power source is a distance away from the pump battery, to provide additional protection against electrical short circuits in the presence of water. Commonly available batteries of between 10 and 24 Volts can be used.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a battery-powered water pump for providing for the recirculation of hot water so as to provide immediate hot water when a tap is turned on utilizing a minimal sized pump to provide the additional small amount of pressure differential required for this recirculation in a normal single family home with a water heater tank, for example as is typical in the U.S.

2. Description of the Related Art

In many of the dry, or drought-plagued parts of North America, and possibly elsewhere, hot water is often continually circulated within the closed water system of a house or business, in order to have hot water substantially immediately available when a faucet is turned on; this avoids, or at least reduces, the wasting of flowing water while waiting for the hot water to reach a tap in a bathroom or kitchen of a home or office center. By circulating the hot water continuously to the most distant hot water tap, it becomes substantially immediately available at various other tap points in a system as needed.

Some systems, instead of continuously circulating the water in the system, a pump can be made to operate in a continual pulse mode, i.e., on for a period and off for a period, on a continuing basis. For example, a pulse mode can comprise 150 seconds on and 10 minutes off, all day, every day, or only during certain pre-programmed periods. The prior devices all utilized house current to power relatively inefficient pumps, located either at or near the hot water tank, especially for new house construction, or located at the farthest tap site and pumping between the hot and cold water lines at those locations, for aftermarket installation in older buildings. The pump motors were powered by AC current. Examples of prior art systems are shown in FIGS. 1A and 1B; in FIG. 1A, a system in a newly constructed residence is shown where the water pump is located adjacent the water heater and is operated by electronic controls. Such a system has been offered and sold by Taco, Inc., as an ON COMMAND™ SYSTEM for Re-Circulation Piping, which includes specially prepared and installed piping for recirculating the hot water directly back to the water heater, whether the heater includes a hot water tank or is a so-called “tankless water heater”. In all cases, these prior art systems all required a socket for the house AC current to power the pump motor, which in the case of the under sink, post-construction system, required calling in an electrician to install a socket at the undersink location meeting local safety codes.

In FIG. 1B is shown a system that could be installed, under a sink, for example, in an older house without changing the overall house piping, but requiring the installation of a special under sink electric socket, also as exemplified by an ON COMMAND™ system, from Taco, Inc.

BRIEF SUMMARY OF THE INVENTION

The present invention reflects the novel recognition that a relatively small pump-motor combination powered by batteries can provide sufficient pump power to create the flow necessary to maintain a substantially immediate hot water response when the hot water tap is opened, even at the tap farthest from the building hot water heater. Preferably, each of the batteries is rechargeable, most preferably utilizing a wireless system where the power source is a distance away from the battery, e.g., on a wall or in the ceiling of the bathroom or kitchen, to provide additional safety against electrical short circuits in the presence of water. The water pump comprises a water pump mechanism coupled to a DC motor powered by batteries. In the preferred systems, the batteries are in turn coupled to a charger unit, that most preferably receives power wirelessly from a distant, across the room, source. There are also wireless power transmitters being developed for allowing a single power source to wirelessly charge batteries throughout an entire house. Commonly available batteries of between 10 and 24 Volts can be used, and many are rechargeable using common household current.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a diagram of a prior art 110V AC-powered pump installed in a hot water system of a newly constructed house, with a dedicated hot water return line;

FIG. 1B is a diagram showing a possible location of a prior art pump installed in a retrofitted hot water system of a house that does not have a dedicated hot water return line;

FIG. 1C is a close-up picture showing the pump of FIG. 1B retrofitted between the hot and cold water lines under a sink in a house;

FIG. 2 is a diagrammatic sketch representing the retrofitted connection of the DC, battery-powered, motor pump of this invention, into the previously constructed plumbing system of a house;

FIGS. 3A, B are isometric drawings of different views of a preferred battery-powered DC motor pump of the present invention;

FIG. 4 is an exploded isometric view showing the internal construction of one example of a battery-powered pump of the present invention;

FIG. 5 is a diagrammatic picture showing a preferred example of a wirelessly rechargable, battery-powered motor pump of the present invention, and a broadcast power transmitter at one preferred location in a bathroom;

FIG. 6A is an isometric drawing of an example of a wirelessly rechargable battery-powered DC motor pump of the present invention;

FIG. 6B is an exploded isometric view showing the internal construction of an example of a wirelessly rechargable, battery-powered DC motor pump of the present invention, shown in FIG. 6A;

FIG. 7 is a highly diagrammatic sketch showing the AC powered broadcast transmitter, located at a distance from the transmitter, the power receiver and circulator, with charger powered from the broadcast power receiver; and

FIG. 8 is a highly diagrammatic sketch showing the broadcast power receiver and circulator with charger powered from the broadcast power receiver, together with the battery powering the pump motor and the controller and Drive for operating the pump in accordance with this invention.

DETAILED DESCRIPTION

Referring to FIGS. 2-4, there is shown an example of a battery-powered circulator system of the present invention which comprises an electronically controlled water circulator mechanism, generally indicated by the numeral 25 (powered by a battery 30),coupled between the hot and cold water tap lines 17 and 19, respectively, under, e.g., the sink farthest from the water heater 15. By circulating the hot water to this tap, all intervening taps, including showers, are also made available to substantially instant hot water.

The circulator system includes an electronic controller unit 7, provided with a digital readout 8, which controls the operation of the battery-powered DC motor pump with respect to turning the pump on or off at specified times, i,e., determining when and how often the hot water is to be circulated. In addition, in another embodiment there can also be provided a thermistor, or temperature sensor, that locks out the controller from starting circulation if the temperature in the hot water line is above a preset value, e.g., 100° F., OR stops the pump when the hot water temperature has increased a preset ΔT, e.g., 10° F. after the circulator began operation. This electronic controller/thermistor control system, and the pump motor, shown as stator 3 and rotor 2, are all powered by the battery unit 1, which in one of the preferred embodiments (FIGS. 3A,B and 4) includes a recharging unit powered through a wire directly to a socket in the wall of the house adjacent the tap; and in a second, even more preferred embodiment (FIGS. 5 and 6A,B), includes a wireless power receiver for receiving transmitted power from a distant power source, e.g., on a wall across the room from the tap to recharge the battery.

Most generally, the invention is based upon the novel recognition that a small, low power pump can provide the necessary pressure differential needed to cause circulation of the water from the water heater, into the hot water line, to the cold water line and back to the water heater from the cold water line. Both of the hot and cold water lines, when the taps are all closed, have substantially the same line pressure, so that only a small pressure differential is required from the pump to circulate the water in the hot water line into the cold water line, and thus draw in fresh hot water into the hot water line from the hot water heater. This allows for an efficient low pressure circulator, such as the wet rotor, centrifugal, DC motor-driven pump shown in the drawings, which can draw as little as 1-5 watts of electrical power when it is operating. It was also realized that the pump need only operate during a few minutes of each hour in order to maintain instant hot water, in most modem insulated homes, even in the coldest weather met in the contiguous 48 states of the United States, i.e., temperate North America.

The energy use of the pump will be over a short period of time. Therefore, although a battery is generally more rapidly discharged than re-charged, the rapid discharge period during pump operation, will continue for only a relatively short period of time, e.g., for about 12 minutes of each hour. The wireless charger power capacity can then be significantly smaller, as it will be able to charge over a longer period of time, than the battery is discharging. This has the benefit of permitting the use of lower cost components, and results in a reduced risk of overcharging the battery.

As shown, the circulator is located between the most distant location from the hot water heater, in the building, containing both a hot and a cold water tap, e.g., in a single sink. The circulator connects to the hot and cold water lines under the sink, through standard NPT connections, 9 or 10 and 109 or 110 fittings, respectively, depending upon the layout of the original plumbing under the sink. The thermistor measures the temperature of the water on the hot water side of the pump, and sends its signal to the controller. The thermistor sensor can preferably be molded into the wall of the pump casing inlet 105.

In one preferred embodiment, as shown in FIGS. 3A, B and 4, as well as in FIGS. 5-6B, the circulator system includes an outer housing or shell, including a pump rotor casing 22, which includes the pump inlet and outlet 105 and 106, a wet rotor cartridge assembly 65 formed from permanent magnets 2, and a stator 3, formed of wire-wound soft magnetic core material, surrounding the rotor and connected to the DC power supply, e.g., a battery. The stator is held within a motor housing 57, which is connected to the electronics enclosure 5, holding the programmable electronic timer and digital readout 7, 8. The motor fits within its housing 4, part of the overall system housing 1; the rotor 2 is mechanically directly connected to a centrifugal impeller 42, located within the pump casing 22, which operates to circulate the water between the hot water inlet line 9, 10 and the cold water outlet line 109,110.

The pump motor is capable of drawing electric power in a range up to 12 Watts, but usually as little as 1-5 watts is sufficient, as a pressure head of not more than 5 ft, is sufficient to circulate the water for this purpose, as the differential between pressure heads in the hot and cold water lines are usually on the order of 1-2 ft, or less. Similarly, a maximum flow rate of between 1 and 5 gpm will generally be sufficient for this purpose, so that larger, more powerful pumps are not preferred. For such pumps ⅜ in. or ½ in. npt connections would be sufficient. All connections and materials of construction will have to meet regulatory requirements, such as the NSF/ANSI 372 requirements, or other local jurisdiction requirements.

As shown, the wired charger of FIGS. 3A, B and 4 must be connected to a wall socket to reach the house current, in order to recharge the battery. The recharger unit is housed within the upper plastic casing 1, adjacent the battery unit 6. For longevity and compact size, a 12 V or 24 V Lithium Ion battery is preferred, although a slightly larger NiCd battery would also be useful.

In the event a battery requires recharging, it can be removed and charged in an external location from the pump system, and a substitute battery inserted during the charging period. Alternatively, the battery within the circulator system can be electrically connected to a charger which in tutu is electrically connected to a source of electric power such, as a house current socket in the wall of a room. In order for that to be a permanent connection, it is necessary for the socket to be reasonably close to the pump location, which in many jurisdictions requires a special socket construction to avoid a short circuit due to the potential of wet conditions near a water tap, e.g., in a bathroom or kitchen.

Referring to the wirelessly rechargeable, battery-powered DC motor pump of FIGS. 5-6B, numeral 51 generally indicates the Wireless Power Transfer Pumping System of the present invention, which includes a broadcast power receiver connected to the battery charger, and 52 designates a wireless power transmitter on the wall or the ceiling of a bathroom or kitchen.

In the wireless pumping system 51, the motor housing 57 covers and protects the motor and the battery and charger housing 52 covers the battery 61 which is electrically connected to the motor stator windings 56, and to the electronic controller 58, within the electronics housing 59, which controls the operation of the motor, and thus the circulator pump. The casing 55 covers and protects the centrifugal pump impeller 65, which is operationally connected to the wet rotor cartridge assembly 54 of the low voltage DC pump motor. The wet rotor 54 in this case is preferably formed of permanent magnets, such as is disclosed in copending, commonly owned U.S. Patent application No. 61/716,060, filed Oct. 19, 2012. A low voltage DC motor stator 56 surrounds the rotor 54 and is electrically connected to the battery 61. The battery 61 is adjacent to and electrically connected to a recharger, also located within the housing 52, which in turn is connected to the wireless power receiver 63. A cover 71 closes off the end of the electronics housing 59, surrounding the readout 8, as a protective seal.

The preferred wirelessly rechargeable version of this invention avoids the problem of constructing special sockets for a wired recharger by placing the power broadcaster away from the water location and broadcasting the power to the broadcast receiver adjacent the charger. Although no commercial such units are presently available, there are many designs that could be used. One such example, which is effective over distances of more than two meters, is described in U.S. Patent Publication 2011/0025131. The theory behind the wireless power transfer was described in a SCIENCE article from 2007, Vol. 317, pp 83-86, entitled Wireless Power Transfer Via Strongly Coupled Magnetic Resonances, by Andre Kurs et al. Kurs utilizes nonradiative (so-called “near-field”) magnetic resonant induction at megahertz frequencies, to achieve nonradiative wireless power transference.

In a further advance, the Toyota automobile company has developed a system for recharging electric powered vehicles using power broadcast over a distance of about two meters, or more, as described in U.S. Patent Publication No. 2010/0295506, utilizing nonradiative near-field magnetic resonant induction. One such broadcast system useful for the present invention, in accordance with the Kurs concept, is diagrammatically shown in FIGS. 7-8, where the source of power for the nonradiative near-field magnetic resonant induction primary coil 200 is a house AC circuit. The primary coil 200 can be located either at a wall across the room, or above the pump in the ceiling, as long as the sink will not present significant interference to the magnetic resonant field, preventing its contacting the secondary wireless receiver coil 205, usually located under the sink, adjacent the battery and charger, as in FIG. 5.

FIG. 8, diagrammatically details the power storage and recharger system, shown within a dashed line and generally designated by the reference numeral 250, comprising the secondary receiver coil 205 and the intervening recharging system 210, which comprises a bulk capacitor 210 and a charger 230. The wireless receiver 205 feeds current to the bulk capacitor which holds the charge until reaching its design discharge voltage level, as controlled by the circuit in the charger 230, when it begins to discharge at a level suitable to be received by the battery 215. The controller 212 and the motor pump 51 are all powered from the power storage unit, in this case a rechargeable storage battery 215. The low power requirement of the pump/motor/drive system 51, unlike the automobile motors in the Toyota system, can operate directly from the battery voltage without requiring a voltage step-up. The capacitor serves to cache, or pool, the power received from the wireless receiver 205 until it reaches a suitable voltage.

Alternative power storage units include a super capacitor of large capacitance, but a chemical storage battery, such as a lithium-ion battery, lithium-ion polymer battery, nickel-metal hydride (NiMH) battery, nickel cadmium (NiCd) battery, or even a lead acid battery, is preferred for this type of low power application, among the rechargeable power sources presently commercially available.

The above examples and descriptions are intended to be exemplary only. It is understood that one of ordinary skill in the art will comprehend the full scope of this invention to be set only by the scope of the claims set forth below. 

What is claimed is:
 1. A battery-powered motor-pump combination to promptly provide for a building hot water system hot water at every tap following lengthy periods of nonuse, the pump system comprising: a time controller for the motor-pump combination; a centrifugal pump impeller and casing, the casing having a water inlet and a water outlet; an electrical power storage unit; a DC electric motor, controlled by the timer controller, electrically connected to the battery and able to be powered by the chemical battery and mechanically connected to the centrifugal pump impeller to provide the power to operate the pump combination; the pump system being designed to be connected by the water inlet to the pressurized hot water line in the building, upstream of a hot water tap, and designed to being connected by the water outlet to the pressurized cold water line in the building, upstream of a cold water tap; the pump system designed when operating to recirculate hot water from the hot water line into the cold water line in response to commands from the time controller to turn on and off the electric motor and thus cause the impeller to turn and stop,
 2. The battery-powered motor-pump combination of claim 1 wherein the electrical power storage unit is a chemical storage battery.
 3. The battery-powered motor-pump combination of claim 2 wherein the storage battery is rechargable, and further comprising an electric charger to recharge the storage battery when the storage battery loses sufficient charge so that it cannot effectively power the motor
 4. The battery-powered motor-pump combination of claim 2 wherein the charger comprises a power lead designed to receive electrical power from a house wall socket.
 5. The battery-powered motor-pump combination of claim 2, further comprising a broadcast power receiver designed to receive broadcast power from a correspondingly tuned power broadcast transmitter located at a distance from the battery-powered motor-pump combination and electrically connected to the charger so as to provide power to the charger for recharging the storage battery.
 6. The battery-powered motor-pump combination of claim 2, further comprising a thermistor operatively connected to the time controller and to the motor-pump combination, so as to prevent increasing the temperature in a hot water line beyond a preset value.
 7. A battery-powered pump system for a building hot water system to promptly provide hot water at every tap, following lengthy periods of nonuse, the pump system comprising: a time controller for the pump system; a centrifugal pump impeller and casing, the casing having a water inlet and a water outlet; a storage battery; a DC electric motor, controlled by the timer controller, electrically connected to the battery and able to be powered by the chemical battery and mechanically connected to the centrifugal pump impeller to provide the power to operate the pump system; a pressurized hot water line in the building and a pressurized cold water line in the building; the pump system being connected by the water inlet to the hot water line, upstream of a hot water tap and being connected by the water outlet to the cold water line, upstream of a cold water tap; the pump system operating to recirculate hot water from the hot water line into the cold water line in response to commands from the timer controller to turn on and off the electric motor and thus cause the impeller to turn and stop.
 8. The pump system of claim 7 further comprising a signal interface circuit, a thermistor, and an automatic operation switch, the signal interface circuit coupling the thermistor, and automatic operation switch to the timer controller for controlling the operation of the pump system, the thermistor being capable of over-riding the switches to limit the temperature in the hot water line upstream from the hot water tap.
 9. The pump system of claim 7 where the battery has an electrical voltage rating of between 10 and 24 volts.
 10. The pump system of claim 7, further comprising a compact casing for the pump system, the battery being integrated with and housed within the compact casing for the water pump system.
 11. The pump system of claim 5, wherein the pump motor comprises a rotor formed of permanent magnets and a wire-wound stator electrically connected to the battery
 12. The pump system of claim 5, wherein the electric motor can operate on at least 5 Watts power, and provides a maximum pressure head of at least 5 ft of pressure head and a maximum flow output of at least 5 gpm.
 13. A wireless pump system for a building hot water system to promptly provide hot water at every tap, following lengthy periods of nonuse, the pump system comprising: a time controller for the pump system; a centrifugal pump impeller and casing, the casing having a water inlet and a water outlet, the pump impeller being wholly encompassed within the casing; a rechargeable electrical storage battery; a DC electric motor, controlled by the timer controller, electrically connected to the battery and able to be powered by the storage battery and mechanically connected to the centrifugal pump impeller to provide the power to operate the pump system; a pressurized hot water line in the building and a pressurized cold water line in the building; the pump system being connected by the water inlet to the hot water line, upstream of a hot water tap and being connected by the water outlet to the cold water line, upstream of a cold water tap; a charger unit electrically connected to the storage battery and operating from time to time to recharge the battery; and a wirelessly broadcast power receiver, in electrical connection with the charger unit, the wirelessly broadcast power receiver receiving power broadcast from a power broadcaster located at a distance from the receiver, the receiver being adjacent the charger and the pump motor; the pump system operating to recirculate hot water from the hot water line into the cold water line in response to commands from the timer controller to turn on and off the electric motor and thus cause the impeller to turn and stop, and the charger capable of receiving broadcast power and recharging the storage battery as needed.
 14. The wireless pump system of claim 12 further comprising a compact casing encompassing the complete wireless pump system.
 15. The wireless pump system of claim 13, wherein the rotor is mechanically directly connected to the pump impeller.
 16. The wireless pump system of claim 13, wherein the pump motor comprises a rotor formed of permanent magnets and a wire-wound stator electrically connected to the battery.
 17. The wireless pump system of claim 12, wherein the electric motor can operate on at least 5 Watts power, to provide a maximum pressure head of at least 5 ft of pressure head and a maximum flow output of at least 5 gpm.
 18. The pump system of claim 12, further comprising a compact casing for the pump system, the battery, charger and broadcast power receiver being integrated with and housed within the compact casing for the water pump system.
 19. A building water flow system that provides substantially instantaneous hot water from hot water taps without regard to the length of time between use, the system comprising: a source of hot water; multiple hot water taps; and a closed piping system providing a fluid flow connection between the source of hot water and each of the multiple hot water taps; a source of ambient water; multiple ambient water taps located adjacent at least the hot water tap located the furthest front the source of hot water; and a closed piping system providing a fluid flow connection between the source of ambient water and each of the is multiple ambient water taps, and between the source of ambient water and the source of hot water; a battery-powered motor-pump combination comprising: a time controller for the motor-pump combination; a centrifugal pump impeller and casing, the casing having a water inlet and a water outlet; an electrical storage battery; a DC electric motor, controlled by the timer controller, electrically connected to the battery and able to be powered by the chemical battery and mechanically connected to the centrifugal pump impeller to provide the power to operate the pump combination; the water inlet being connected to the pressurized hot water line in the building, upstream of a hot water tap the furthest from the source of hot water, and the water outlet being connected to the pressurized cold water line in the building, upstream of the cold water tap adjacent the furthest hot water tap; the pump system being designed to recirculate hot water from the hot water line into the cold water line in response to commands from the timer controller to turn on and off the electric motor and thus cause the impeller to turn and stop, thus constantly refreshing the hot water in the hot water line.
 20. The building water flow system of claim 18 wherein the storage battery is rechargable, and further comprising an electric charger to recharge the storage battery when the storage battery loses sufficient charge so that it cannot effectively power the motor, a broadcast power transmitter and a broadcast power receiver designed to receive broadcast power from a correspondingly tuned power broadcast transmitter located, at a distance from the battery-powered motor-pump combination and electrically connected to the charger so as to provide power to the charger for recharging the storage battery. 